Rotatable crown for an electronic device

ABSTRACT

A compact crown for an electronic device such as an electronic watch, including a set of wipers capable of determining a rotation angle, rotation direction, or rotation speed, is disclosed. The set of wipers is in contact with at least one resistance member at different angular positions around a rotation axis. The crown may have a group of ground taps disposed along the resistance member and a measured signal may vary based on the position of each wiper as it contacts the at least one resistance member. A compact crown may also include capacitive members and capacitive sensors in order to similarly determine rotation angle, rotation direction, or rotation speed.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a nonprovisional patent application of and claimsthe benefit of U.S. Provisional Patent Application No. 62/337,804, filedMay 17, 2016 and titled “Compact Rotary Encoder,” the disclosure ofwhich is hereby incorporated herein by reference in its entirety.

FIELD

The described embodiments relate generally to compact crowns forelectronic devices such as electronic watches. More particularly, thepresent embodiments relate to a crown having (or taking the form of) ahigh-resolution rotary encoder that detects a rotation angle or relativeamount of motion using an output from two or more angularly offsetwipers.

BACKGROUND

In computing systems, a rotary encoder may be employed to detect anangular position or motion of a shaft. Many traditional rotary encodersuse optical sensing of indicia placed around a circumference of anencoder surface or wheel. The precision of such rotary encoders istherefore limited by the minimum achievable size and spacing of theindicia. Optical sensing of indicia may also limit the ability of atraditional rotary encoder to detect a direction of rotation of arotatable shaft of the encoder.

SUMMARY

Embodiments of the present invention are directed to a crown for anelectronic device, which crown may be configured to determine an angularposition, direction of rotation, or speed of rotation of auser-rotatable shaft or other user-rotatable element, for example, tocontrol a function of the electronic device. The controlled function mayinclude, for example, a graphical output of a display on the electronicdevice or a volume of an audio output of the electronic device.

In a first aspect, the present disclosure describes an electronic watch.The electronic watch includes a housing; a crown at least partiallypositioned within the housing and configured to receive rotational andtranslational input from a user, and comprising: a shaft; a resistancemember; and a set of wipers affixed to the shaft and operative to travelalong the resistance member during rotation of the shaft, the set ofwipers providing an output based on multiple contact points between theset of wipers and the resistance member; a display positioned at leastpartially within the housing and configured to depict a graphic inresponse to at least one of the rotational or translational input; ananalog-to-digital converter electrically connected to the set of wipers,the analog-to-digital converter configured to provide a digital outputcorresponding to the output; and a processor configured to determine anangular position, direction of rotation, or speed of rotation of theshaft using the digital output, and to manipulate the graphic inresponse to the determined angular position, direction of rotation, orspeed of rotation; wherein each wiper divides a resistance of theresistance member at each contact point, and a voltage at each contactpoint of the multiple contact points varies in response to rotation ofthe shaft.

Another aspect of the present disclosure may take the form of a methodfor controlling an electronic watch, comprising: receiving an outputsignal from a crown of the electronic watch; identifying, based on theoutput signal, a first angle of rotation of a first wiper of the crownabout an axis of a shaft of the crown, the first wiper in contact with aresistive track or a conductive output track of the crown; identifying,based on the output signal, a second angle of rotation of a second wiperof the crown about an axis of the shaft of the crown, the second wiperin contact with the resistive track; and controlling a function of theelectronic watch based on at least one of the first and second angles ofrotation.

Still another aspect of the disclosure may take the form of a crown foran electronic watch, comprising: a resistance member on a contactsurface; a user-rotatable shaft; an array of ground taps separating theresistance member into segments of uniform resistivity; a first wiperand a second wiper affixed to the user-rotatable shaft, the first wiperconfigured to generate a first output and the second wiper configured togenerate a second output based on a relative position of the first wiperor the second wiper with respect to the resistance member; and aprocessor configured to determine at least one of an angular position, adirection of rotation, or a speed of rotation of the user-rotatableshaft based on the first output and the second output, wherein the firstwiper and the second wiper are affixed to the user-rotatable shaft suchthat the first wiper contacts the resistance member at a first segmentthat is distinct from a second segment contacted by the second wiper.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thedrawings and by study of the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIG. 1 shows a sample electronic device that may incorporate a rotaryencoder in the form of a crown, as described herein;

FIG. 2 shows an electrical block diagram of the electronic device ofFIG. 1;

FIG. 3 shows a sample rotary encoder according to one exampleembodiment;

FIG. 4 shows a simplified electrical diagram of the rotary encoder ofFIG. 3;

FIGS. 5A-5B show sample circuit diagrams formed by the rotary encoder ofFIG. 3;

FIGS. 6A-6B show sample voltage vs. position graphs of the rotaryencoder of FIG. 3;

FIG. 7 shows a simplified electrical diagram of a rotary encoderaccording to another example;

FIGS. 8A-8B show sample voltage vs. position graphs of the rotaryencoder of FIG. 7;

FIGS. 9A-9B show a simplified electrical diagram of a rotary encoderaccording to another example;

FIG. 10 shows a sample circuit diagram formed by the rotary encoder ofFIG. 9;

FIG. 11 shows a sample voltage vs. position graph of the rotary encoderof FIG. 9;

FIG. 12 shows a timing diagram for the rotary encoder of FIG. 9;

FIG. 13 shows a simplified electrical diagram of a rotary encoderaccording to another example;

FIG. 14 shows a sample circuit diagram formed by the rotary encoder ofFIG. 13;

FIG. 15 shows a simplified electrical diagram of a rotary encoderaccording to another example;

FIG. 16 shows a sample circuit diagram formed by the rotary encoder ofFIG. 15;

FIG. 17 shows a sample voltage vs. position graph of the rotary encoderof FIG. 15;

FIG. 18 shows another example of a rotary encoder;

FIG. 19 shows a top view of a portion of the rotary encoder of FIG. 18;

FIGS. 20A-20B show sample capacitance vs. position graphs of the rotaryencoder of FIG. 18; and

FIG. 21 illustrates a method that may be performed to control a functionof an electronic device based on an angle of rotation of a wiper of arotary encoder about an axis of a rotatable element of the rotaryencoder.

FIG. 22A illustrates a list, displayed on an electronic device, that maybe controlled by rotation of a crown.

FIG. 22B illustrates the list of FIG. 22A, changed in response torotation of the crown.

FIG. 23A illustrates an electronic device displaying a picture, themagnification of which may be controlled by rotation of a crown.

FIG. 23B illustrates the picture of FIG. 23A, changed in response torotation of the crown.

FIG. 24A illustrates an electronic device displaying a question that maybe answered by rotating a crown.

FIG. 24B illustrates the electronic device of FIG. 23A, with thequestion answered through rotation of the crown.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following descriptions are not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

The following disclosure relates to a compact rotary encoder capable ofhigh resolution output for use in an electronic device such as anelectronic watch. More particularly, the rotary encoder may be used as,or connected to, a crown of an electronic watch. The crown may functionas an input device of the electronic device, and may be selectivelyrotated about an axis. The relative rotation around the axis may be usedto control a feature, interface, or other mechanism of the electronicdevice. The high resolution of the rotary encoder, functioning as acrown (or as part of a crown), may allow for precise control of anelectronic device. In some examples, the rotary encoder may control orvary any or all of: a graphic shown on a display on the electronicdevice; a function of the electronic device; a haptic output of theelectronic device; and/or a volume of an audio output of the electronicdevice.

In an embodiment, the crown (e.g., rotary encoder) may have auser-rotatable shaft, at least two arms extending radially from theshaft and separated by an angle, and a wiper or slider coupled to eacharm. Each wiper may extend from the arm at an angle and contact at leastone resistance member on a contact surface of a rotary encoder base. Insome embodiments, the arms may extend at a non-right angle from theshaft. In some examples, the arms may be replaced by one or more rotors,or by a portion of the shaft that extends outward from an axis of thecrown, which portion provides or supports the wipers, sliders, or otherelectrical contact members. The contact surface may also have a group ofground taps electrically coupled to the resistance member and at leastone conductive element disposed radially around the shaft. In someembodiments, the resistance member may form a circle, track, path, orthe like. Further, the resistance member may be divided into multiplesegments.

As the shaft is rotated about its axis (e.g., by a user), each wipercontacts a different portion of the resistance member and experiences avariable resistance as a result of the wiper “dividing” a portion of theresistance member between ground points into at least two segments. Thatis, as the shaft rotates, the wiper varies the length of segments of theresistance member between the wiper contact point and grounded pointsdisposed around the resistance member. The output signals for each wipermay be detected and monitored by a processor to determine a rotationangle (i.e., angle of rotation or angular position), rotation direction(i.e., direction of rotation), or rotation speed (i.e., speed ofrotation) around the shaft axis.

In some embodiments, the at least two arms (or the at least two contactmembers that are otherwise affixed to the shaft) are separated by anangle. This may cause each respective wiper to contact the resistancemember at points at which the output signals are out of phase. Theparticular angle of separation for the arms (or contact members) may bechosen such that the output signals from the wipers, when plotted as afunction of the rotation angle, are signals in quadrature (e.g., signalsseparated by a predetermined offset). Accordingly, by determining thephase difference between signals from the respective wipers, a directionof rotation can be determined.

In another embodiment, the rotary encoder/crown may have a shaft and atleast two capacitive members extending radially from the shaft andseparated by an angle. The capacitive members may rotate above the baseof the rotary encoder member. The base of the rotary encoder/crown mayinclude a set of capacitance sensors positioned on a sensing surfacebeneath the shaft. The capacitance sensors may be coaxial with theshaft. The capacitive sensors may detect a capacitance betweenthemselves and the capacitive members. As the shaft rotates, thecapacitive members may pass over the capacitive sensors. Capacitancebetween a capacitive member and a capacitive sensor increases as overlapbetween the member and sensor increases, and decreases as overlapdecreases. The capacitive member may revolve as the shaft rotates,thereby varying the overlap of the capacitive member with respect to thecapacitive sensor. As the shaft rotates, this overlap may vary from zeroto full, or anywhere in between.

The capacitive members and the group of capacitance sensors may beconfigured to maintain a constant separation during rotation of thecapacitive members around the shaft axis. The output signals of thecapacitance sensors may be detected and monitored by a processor todetermine a rotation angle, rotation direction, or rotation speed of theshaft around the shaft axis.

These and other embodiments are discussed below with reference to FIGS.1-21. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these Figures is forexplanatory purposes only and should not be construed as limiting.

Turning now to the figures, FIG. 1 illustrates an electronic device 100such as a wearable electronic device, timekeeping device, portablecomputing device, mobile phone, touch-sensitive input, or the like. Theelectronic device 100 may have a housing 102 defining a body, a display104 configured to depict a graphical output of the electronic device100, and at least one input device or selection device 106. An inputdevice 106 may be positioned at least partially within the housing 102and may project through the housing so that a user may manipulate theinput device (for example, by rotating it). Likewise, the display 104may be positioned at least partially within the housing 102 and may beaccessible by, and visible to, a user. The user may view informationpresented on the display and may touch the display to provide a touch orforce input. As one example, the user may select (or otherwise interactwith) a graphic, icon, or the like presented on the display by touchingor pressing on the display at the location of the graphic.

The electronic device 100 may have a band 108 for securing theelectronic device 100 to a user, another electronic device, a retainingmechanism, and so on. In some embodiments, the electronic device 100 maybe an electronic watch, the body defined by the housing 102 may be awatch body, and the input device 106 may be a crown of the electronicwatch. The crown may extend from an exterior to an interior of theelectronic device housing. The crown may be configured to receiverotational and translational input from a user. The input device 106 mayinclude a scroll wheel, knob, dial, or the like that may be operated bya user of the electronic device 100. Some embodiments of the electronicdevice 100 may lack the band 108, display 104, or both.

The electronic device 100 may include a number of internal components.FIG. 2 illustrates a simplified block diagram 200 of the electronicdevice 100. The electronic device 100 may include, by way ofnon-limiting example, one or more processors 202, a storage or memory204, an input/output interface 206, a display 210, a power source 212,and one or more sensors 208, each of which will be discussed in turnbelow.

The processor 202 may control operation of the electronic device 100.The processor 202 may be in communication, either directly orindirectly, with substantially all of the components of the electronicdevice 100. For example, one or more system buses 201 or othercommunication mechanisms may provide communication between the processor202, the display 210, the input/output interface 206, the sensors 208,and so on. The processor 202 may be any electronic device capable ofprocessing, receiving, and/or transmitting instructions. For example,the processor 202 may be a microprocessor or a microcomputer. Asdescribed herein, the term “processor” is meant to encompass a singleprocessor or processing unit, multiple processors, or multipleprocessing units, or other suitably configured computing element(s).

In some examples, the function(s) of the electronic device 100controlled by the processor 202 may include a graphical output of adisplay 210 on the electronic device 100. For example, in response todetecting rotation of the input device 106 (e.g., a changed angularposition, direction of rotation, or speed of rotation of a rotaryencoder, which rotary encoder may be a crown or part of a crown), theprocessor 202 may change or manipulate (e.g., scroll, zoom, pan, move,etc.) a graphic depicted on the display 210. Scrolling may be within agraphic (e.g., a photo or map), within text and/or images of a documentor web page (which are specific examples of graphics), within an arrayof graphics representing applications or functions that may be selected,launched, and so on. The processor 202 may cause graphics on a displayto scroll in a particular direction based on a determined direction ofrotation of the input device 106, or may cause scrolling at a speedbased on a determined speed of rotation of the input device 106. FIGS.22A-24B, discussed below, provide examples of how a rotatable inputdevice 106, such as a crown, may be used to interact with an electronicdevice and manipulate or change graphics on an associated display.

As another example, rotating the input device 106 may cause differentgraphics, icons, information, or the like to be shown on the display sothat a user may select or otherwise interact with suchgraphics/icons/information (collectively, a “graphic”). The user mayinteract with a graphic by touching or applying force to a portion ofthe display 104 depicting the graphic, through rotational input to theinput device 106, through translational input to the input device 106(e.g., pressing a crown toward the housing of the electronic device),and so on.

The processor 202 may also or alternatively adjust a volume of an audiooutput of the electronic device 100 in response to detecting rotation ofthe input device 106. The volume may be adjusted up or down based on adirection of rotation of the input device 106. The processor 202 mayalso or alternatively adjust other settings of the electronic device 100(or settings of applications hosted on or accessed by the electronicdevice 100) in response to detecting rotation of the input device 106(e.g., the processor 202 may adjust the time displayed by a clockfunction of the electronic device 100). In some examples, the processor202 may control movement of a character or item within a game based on adetected rotation (change in angular position), direction of rotation,or speed of rotation of the input device 106.

In some examples, the function of the electronic device 100 controlledby the processor 202 may be determined based on a context of theelectronic device 100 or processor 202. For example, the processor 202may adjust a volume of an audio output of the electronic device 100 whenthe input device 106 is rotated while an audio player is open or activeon the electronic device 100, or the processor 202 may scroll throughgraphics representing applications or functions when the input device106 is rotated while a home screen is displayed on the electronic device100.

The memory 204 may store electronic data that may be utilized by theelectronic device 100. For example, the memory 204 may store electricaldata or content (e.g., audio files, video files, document files, and soon), corresponding to various applications. The memory 204 may be, forexample, non-volatile storage, a magnetic storage medium, opticalstorage medium, magneto-optical storage medium, read only memory, randomaccess memory, erasable programmable memory, or flash memory.

The input/output interface 206 may receive data from a user or one ormore other electronic devices. Additionally, the input/output interface206 may facilitate transmission of data to a user or to other electronicdevices. For example, in embodiments where the electronic device 100 isan electronic watch, the input/output interface 206 may be used toreceive data from a network, other electronic devices, or may be used tosend and transmit electronic signals via a wireless or wired connection(Internet, Wi-Fi, Bluetooth, and Ethernet being a few examples). In someembodiments, the input/output interface 206 may support multiple networkor communication mechanisms. For example, the input/output interface 206may pair with another device over a Bluetooth network to transfersignals to the other device, while simultaneously receiving data from aWi-Fi or other network. The input/output interface 206 may receive inputsignals from the sensors 208 and the processor 202 may control theinput/output interface 206 to output control signals for the electronicdevice 100.

The power source 212 may be substantially any device capable ofproviding energy to the electronic device 100. For example, the powersource 212 may be a battery, a connection cable that may be configuredto connect the electronic device 100 to another power source such as awall outlet, or the like.

The sensors 208 may include substantially any type of sensor. Forexample, the electronic device 100 may include one or more audio sensors(e.g., microphones), light sensors (e.g., ambient light sensors),gyroscopes, accelerometers, or the like. The sensors 208 may be used toprovide data to the processor 202, which may be used to enhance or varyfunctions of the electronic device 100. In some embodiments, at leastone of the sensors 208 may be a rotary encoder associated with the inputdevice 106 of the electronic device 100 (e.g., a rotary encoder used as,or connected to, a crown of an electronic watch). In some embodiments,at least one of the sensors 208 may be a dome switch that may bedepressed and activated by user translation of a crown of an electronicwatch.

FIG. 3 illustrates an embodiment of a compact rotary encoder 300 for usein an electronic device, such as electronic device 100. In someembodiments, the rotary encoder 300 may function as the input device 106of the electronic device 100 such that a shaft 306 of the rotary encoder300 rotates when the input device 106 rotates. As one example, the inputdevice (and thus the shaft and wipers) may rotate about a long axis ofthe shaft 306. Such rotation changes the shaft's angular position. Asdiscussed above, in some embodiments, the input device 106 may be therotating crown of an electronic watch. Similarly, any user-rotatableelement may be used in place of a shaft. As previously mentioned, therotary encoder 300, and other rotary encoders discussed herein, may be acrown of an electronic watch, or part of a crown of an electronic watch.Accordingly, discussions herein of rotary encoders should be understoodto include crowns (or bezels, or other rotatable elements) of anelectronic device, such as a watch, phone, tablet computing device,input mechanism, and so on.

The rotary encoder 300 may include a base 302, cover 304, and a contactsurface 303 on the base 302. The cover 304 may include an aperture 308through which a rotating shaft 306 passes, extending into an interior ofthe rotary encoder 300 (or associated device). It should be appreciatedthat the rotary encoder 300 may take the form of a crown, button, scrollwheel, or the like for an electronic device, and the cover 304 may be ahousing of the electronic device. A user may manipulate a portion of therotary encoder to cause the shaft 306 to rotate about an axis extendingalong a length of the shaft, in order to provide an input to theelectronic device.

In some examples, the shaft 306 may be translatable and slide within theaperture 308, such that a terminal end or portion of the shaft isconfigured to depress or otherwise activate a dome switch 322 within thebase 302. Although a dome switch is illustrated, other types of switchesmay be employed and actuated by translation of the shaft. At least twoarms 310 a, 310 b may extend outwardly in a radial direction from theshaft 306. As discussed in more detail with respect to FIG. 4, the arms310 a, 310 b may be coupled to the shaft 306 and separated by a radialangle. It will be appreciated that although two arms 310 a, 310 b areillustrated, more arms may be coupled to the shaft 306 (or otherrotatable element) and separated by other angles. This may improve theresolution or accuracy of the angular position of the shaft detected bythe rotary encoder 300.

Each arm 310 a, 310 b may include a contact member (e.g., a wiper orslider 312 a, 312 b, respectively). The wipers 312 a, 312 b may extendfrom the arms 310 a, 310 b at an angle such that the wipers 312 a, 312 bextend toward, and touch, the contact surface 303 of the base 302. Eachwiper 312 a, 312 b may have a known resistance and may electricallycouple the arms 310 a, 310 b to the contact surface 303 of the rotaryencoder 300. Each wiper 312 a, 312 b contacts the contact surface 303 ata unique wiper contact point. In some examples, the arms 310 a, 310 bmay be provided by one or more rotors, or the arms 310 a, 310 b may bereplaced by a portion (or portions) of the shaft 306 that extendsoutward from the axis of the rotary encoder 300, and the contact membersmay be formed on or attached to a surface of the shaft 306 that facesthe contact surface 303. It should be appreciated that the contactmembers/wipers need not be attached to an arm in any embodimentdescribed herein, but instead may be attached to the shaft or to anotherstructure that ultimately is affixed to the shaft.

The contact surface 303 of the base 302 may have a resistance member314, such as a resistance pad, track, path, or the like providedthereon. In some embodiments, the resistance member 314 may be embeddedinto or integral with the contact surface 303, while in otherembodiments the resistance member 314 may be adjacent, or deposited orotherwise formed on the contact surface 303. As shown in FIG. 3, theresistance member 314 may be disposed in a ring, circle, or other radialpattern around the rotation axis of the shaft 306. The resistance member314 may have a uniform resistivity along its path, circumference,length, or other dimension. The electrical resistance of the resistancemember 314 may be determined by dimensions of the member, such as itsthickness, length, width, density, or other dimension. In some examples,the resistance member 314 may have constant concentrations of materialsuch as gold, copper, silver, or other metals (including alloys),resistive polymers, ceramics, other suitable material, or a combinationthereof to maintain a uniform resistivity. As will be discussed below,the uniform resistivity may be used to determine a position of a wiper312 a, 312 b around the resistance member 314. A constant current source(such as a current regulation circuit) may supply current to theresistance member 314 in certain embodiments. The current source mayprovide a relatively fixed or invariant current, and thus may beconsidered a constant current source.

The contact surface 303 of the rotary encoder 300 may also include aconductive element 316 and a group of ground taps 318 a-d. Theconductive element 316 may be in constant electrical contact with thewipers 312 a, 312 b as they travel along the resistance member 314. Insome embodiments, the conductive element 316 may be embedded or integralwith the resistance member 314, while in other embodiments theconductive element 316 may be positioned above or below the resistancemember 314.

The conductive element 316 facilitates the detection of an electricalsignal provided to the wipers 312 a, 312 b, as discussed further belowwith respect to FIGS. 4 and 5. The wipers 312 a, 312 b may be shaped andangled to maintain electrical contact with the resistance member 314 andthe conductive element 316 throughout rotation of the shaft 306. Asillustrated in FIG. 3, the conductive element 316 may be shapedsubstantially the same as the resistance member 314 (e.g., in the shapeof a circle or ring coaxially aligned with the axis of rotation of theshaft 306). As the shaft rotates, the angular positions of the shaft andthe wipers change, and thus the wipers travel along the resistancemember.

As illustrated in FIG. 3, the four ground taps 318 a-d may be providedat equally spaced locations around the resistance member 314. However,the number of ground taps 318 may vary based on the number of wipers312, the angle between wipers 312, a desired accuracy of the rotaryencoder 300, the number of bits of an analog-to-digital converter (asdiscussed below), and the like. In some embodiments, the ground taps maybe unequally spaced apart from one another.

The rotary encoder 300 may also include a group of electrical contacts320 a-d. The group of electrical contacts 320 a-d may be included in thebase 302 or top 304 and may be electrically coupled to the wipers 312,ground taps 318, conductive element 316, and resistance member 314.Electrical contacts 320 a-d may provide input and output control ofelements of the rotary encoder 300. In some embodiments at least one ofthe electrical contacts 320 a-d may provide an output signal from wiper312 a, an output signal from wiper 312 b, a control signal, a commonground, and the like.

With reference to FIG. 4, a simplified electrical diagram 400illustrates the electrical connectivity of the rotary encoder 300. Asshown in FIG. 4, a resistance member 402 is positioned coaxially arounda shaft 410. A group of ground taps 404 a-d, which may correspond to theground taps 318 a-d, may be provided around the resistance member 402.The total resistance of the resistance member 402 may be R and theresistance member 402 may have uniform resistivity as discussed above(e.g., uniform resistance per unit of material forming the resistancemember 402). That is, when the resistance member 402 has a uniformresistivity, the total or cumulative resistance may be defined as R inthe segment from Θ=0 to Θ=2π. Accordingly, each quadrant Q1-Q4 may havea predefined resistance R_(Q1)-R_(Q4), whereR_(Q1)+R_(Q2)+R_(Q3)+R_(Q4)=R.

As the wiper travels along (e.g., rotates around) and maintains contactwith the resistance member 402 in various locations, the wiper contactpoints 407, 409 form a voltage dividing circuit as discussed below.However, although a resistance member 402 having uniform resistivity hasbeen discussed, it should be noted that the resistance member 402 mayvary its resistance in a known or predetermined manner as a function ofangular displacement around the shaft axis.

Although four ground taps 404 are illustrated in FIG. 4, it should beappreciated that more or fewer ground taps may be provided. Theresolution of the rotary encoder 300 may vary based on the number n ofground taps provided. As shown in FIG. 4, the first wiper 406 (e.g., afirst contact member) and second wiper 408 (e.g., a second contactmember) may be separated by an angle α. This angle α may ensure that thefirst and second wipers 406, 408 output signals in quadrature. Outputsignals that are in quadrature are ones whose phases are offset by apreset amount or predetermined offset. In some embodiments, the angle αmay depend on the number of ground taps. In a particular embodiment, theangle α may be determined by the formula α=π(½n), where n is the numberof ground taps 404.

As illustrated in the example of FIG. 4, a first wiper 406 may contactthe resistance member 402 at a contact point 407 between Θ=0 and Θ=π/2(e.g., quadrant Q1) around the resistance member 402. Put another way,the contact point 407 may define a first portion and a second portion ofthe resistance member 402. Accordingly, when a signal is applied such asa voltage VDD to the first wiper 406, a signal may be measured at thecontact point; this measured voltage varies between VDD and zero volts(e.g., ground). In some embodiments, the voltage at the wiper contactpoint may be measured by including a conductive trace on the wiperitself (not shown). In other embodiments, the signal transmitted throughthe wiper(s) may be read out using a conductive element 316 on orembedded in the contact surface 303 of the base 302 of the rotaryencoder 300 (see FIG. 3). The foregoing generally applies no matterwhich quadrant or at what contact point the wiper contacts theresistance member.

Generally, the voltage at the wiper contact point 407 is a function ofthe position of the first wiper 406 as measured along the resistancemember 402. The wiper's contact point 407 is between two ground taps,unless it is at a ground tap. For example and as shown in FIG. 4, thecontact point 407 is in quadrant Q1 of the resistance member 402,defined as the segment of the resistance member between a first groundtap 404 a and a second ground tap 404 b. The quadrant Q1 may be thoughtof as two separate portions or resistors; namely one resistor R1extending from the first ground tap 404 a to the wiper contact point407, and a second resistor R2 extending from the first ground tap 404 ato the wiper contact point. Each portion R1, R2 will have its ownvoltage, which will vary with the length of the portion (e.g., thedistance from the contact point to an adjacent ground tap).

The second wiper 408 may contact the resistance member 402 at a contactpoint 407 between the ground tap 404 b and 404 c. A third resistance R3may be formed between the contact point of the second wiper 408 and theground tap 404 b. A fourth resistance R4 may be formed between thecontact point of the second wiper 408 and the ground tap 404 c. As willbe discussed below with respect to FIGS. 5A-5B, a circuit may be formedenabling readout of the electrical signal at the contact points of therespective wipers 406, 408.

Similarly, the voltage at the wiper contact point 409 is a function ofthe position of the wiper 408 as taken along the resistance member 402.The wiper's contact point 409 is between two ground taps, unless it isat a ground tap. For example and as shown in FIG. 4, the contact point409 is in quadrant Q3 of the resistance member 402, defined as theportion of the resistance member 402 between a third ground tap 404 cand a fourth ground tap 404 d. The quadrant Q3 may be thought of as twoseparate portions or resistors; namely one resistor R3 extending fromthe third ground tap 404 c to the wiper contact point 409, and a secondresistor R4 extending from the fourth ground tap 404 d to the wipercontact point 409.

It should be noted that the foregoing is but one example of contactpoint locations; the wipers may contact the resistive track at anypoints in any quadrants (or any segment between two ground taps, if theresistive track is not separated into quadrants). Accordingly, anyportion of the resistive track between two ground points (e.g., anysegment) may be modeled as two resistors that have resistances varyingwith distance between the contact point and ground tap.

The circuit shown in FIG. 5A represents the first wiper 406 contactingthe resistance member 402. As shown in FIG. 5A, an input signal VDD maybe provided to the first wiper; the first wiper has a wiper resistanceRw. In some embodiments, the first wiper may be the first wiper 406 ofFIG. 4. At the contact point 407 between the first wiper and theresistance member 402, the input signal VDD is voltage divided by thefirst resistance R1 and the second resistance R2, as shown in FIG. 5Aand similarly in FIG. 4. That is, the voltage at contact point 407varies with the resistance Rw of the wiper, R1, and R2. As the wiper 406is rotated to angle Θ around the shaft 410 axis (e.g., as the angularposition of the shaft changes), the first and second resistances R1, R2vary.

An input of an m-bit analog-to-digital Converter (ADC) may beelectrically coupled to the contact point of the first wiper 406 whileits output is electrically connected to a processor 202. The ADC mayhave a reference voltage Vref determined by the ratio of Rw to R, whichis the total resistance of the resistance member 402 as discussed above.In one particular embodiment, the reference voltage Vref may bedetermined by the formula Vref=(VDD*R)/(R+Rw).

The m-bit ADC may output a digitized signal Wd1 of the voltage measuredat the contact point of the first wiper 406 and the resistance member402. The signal at the wiper contact point 407 may be detected andmonitored over time by a processor 202, in order to determine a rotationposition of the first wiper 406 and thus an angular position of theshaft, as discussed below with reference to FIG. 6.

Similar to FIG. 5A, above, FIG. 5B is an example circuit whichrepresents when the second wiper 408 contacting the resistance member402 at contact point 409 (see also FIG. 4). As shown in FIG. 5B, aninput signal VDD may be provided to a second wiper having a wiperresistance Rw. In some embodiments, the second wiper may be the secondwiper 408 as shown in FIG. 4.

At the contact point between the second wiper 408 and the resistancemember 402, the input signal VDD is voltage divided by the thirdresistance R3 and the fourth resistance R4, as shown in FIG. 5B andsimilarly in FIG. 4. That is, the voltage at contact point 409 varieswith the resistance Rw of the second wiper, R3, and R4. As the secondwiper 408 is rotated at an angle Θ around the shaft 410 axis (e.g., asthe angular position of the shaft changes), the third and fourthresistances R3, R4 vary.

An input of an m-bit Analog-to-Digital Converter (ADC) may beelectrically coupled to the contact point of the second wiper 408 andmay provide a digital output to a processor 202. The ADC may have areference voltage Vref determined by the ratio of Rw to R (e.g., thetotal resistance of the resistance member 402). In one particularembodiment, the reference voltage Vref may be determined by the formulaVref=(VDD*R)/(R+Rw). Accordingly, for a given setup with a resistancemember 402 having a total resistance R around its length, and given awiper with a resistance of Rw, the value of Vref may be constant.

With continuing reference to FIG. 5B, the m-bit ADC may output adigitized signal Wd2 of the voltage measured at the contact point of thesecond wiper 408 and the resistance member 402. The signal at the wipercontact point 409 may be detected and monitored over time by a processor202, in order to determine a rotation position of the first wiper 406and thus an angular position of the shaft.

Turning now to FIGS. 6A and 6B, the outputs at wiper contact points 407and 409 (as discussed above in FIG. 5) are plotted as voltages cyclingbetween zero and a maximum voltage Vref. The figure illustrates thewiper contact voltages as functions of wiper angle Θ, which is the anglebetween a wiper's current contact point and a zero-angle point on theresistance member (e.g., where Θ=0). Plot 602 may be a plot of thesignal at the wiper contact point 407 of the first wiper 406, and line604 may be a plot of the signal at the wiper contact point 409 of thesecond wiper 408. As shown in FIG. 6A, as the shaft 410 is rotated(e.g., its angular position changes) causing rotation of the first andsecond wipers 406, 408, the wiper contact point signals vary betweenzero and Vref. The plots 602 and 604 are out of phase by a constant,predetermined offset and thus considered to be in quadrature. The amountof quadrature or predetermined offset may depend on the angle α betweenthe first and second wipers 406, 408. By determining a phase differencebetween plots 602 and 604, the rotational direction around the shaft 410can be determined, as can the shaft's angular position. Suchdetermination may be done by any suitable processor 202.

FIG. 6A depicts plot 602 as leading plot 604 (i.e., positively out ofphase). Accordingly, FIG. 6A may be a plot reflecting rotation of theshaft 410 in a first direction (e.g., clockwise in FIG. 4). Similarly,FIG. 6B depicts plot 602 as lagging plot 604 (i.e., negatively out ofphase). Thus, FIG. 6B may be a plot reflecting rotation of the shaft 410in a second direction (e.g., counter-clockwise in FIG. 4).

Based on the above configuration, the resolution of the rotary encoder300 may be adjusted to meet various design requirements. The resolutionof the rotary encoder 300 may be approximately n*(2{circumflex over( )}m), where n is the number of ground taps 404 and m is the number ofbits in the m-bit ADC. Therefore, in order to increase resolution, onemay provide more ground taps or a higher-bit ADC. Furthermore, one maychoose an ADC and vary the number of ground taps n to increase ordecrease resolution. Conversely, one may choose a number of ground tapsn and vary the number of bits m of the ADC to increase or decreaseresolution. The ADC may be connected electrically to, and providedigital output to, a processor 202, such that the digital output of theADC may be used by the processor 202 to determine an angular position ofthe shaft.

With reference now to FIG. 7, a simplified electrical diagram 700 ofanother embodiment of a rotary encoder 300 is shown, as is also suitablefor use in, or as, a crown of an electronic device. FIG. 7 illustratesthe electrical connectivity of a rotary encoder similar to the rotaryencoder 300 in FIG. 3 but with a single arm (e.g., a rotor) having afirst and second contact member 706, 708 provided thereon. The firstcontact member 706 may be offset by an angle α from the second contactmember 708. Here, α=π.

A resistive track 702 may be positioned coaxially around a shaft 710 (orother user-rotatable element). The first contact member 706 may contactthe resistive track 702 at a first contact point 707. A group ofelectrical sinks 704 a, 704 b (which act as the ground taps previouslydescribed) may be provided around the resistive track 702. The totalresistance of the resistive track 702 may be R, and the resistive trackmay have uniform resistivity as discussed above (e.g., a uniformresistance per unit volume of material forming the resistive track). Asecond resistive track 703 may be positioned radially inward from thefirst resistive track 702 and disposed in a half-circle around the shaft710. The second contact member 708 may contact the second resistivetrack 703 at a second contact point 709. The radius of the secondresistive track 703, which in this example is a half-circle, may be lessthan the radius of the circular resistive track 702. Another group ofelectrical sinks 704 c, d may be spaced around the second resistivetrack 703. In one embodiment, second resistive track 703 may have oneelectrical sink 704 c at one end and another electrical sink 704 d atthe other end.

As illustrated in FIG. 7, the first contact member 706 may contact theresistive track 702 at a first contact point 707 located somewherebetween Θ=0 and Θ=π. Accordingly, when a signal is applied (such as avoltage Vref) to the first contact member 706, an output voltage at thecontact point may vary between Vref and zero volts (i.e., ground).

A third resistance R3 may be established between the contact point ofthe second contact member 708 and the electrical sink 704 c. Similarly,a fourth resistance R4 may be established between the contact point ofthe second contact member 708 and the electrical sink 704 d. As wasdiscussed above with respect to FIGS. 5A-5B, a circuit may be formedenabling readout of the electrical signals at the contact points of therespective contact members 706, 708.

Generally, the voltage at the first contact member's 706 contact point707 is a function of the position of the contact member 706 along theresistive track 702. The contact member's contact point 707 is betweentwo electrical sinks, unless it is at an electrical sink. For exampleand as shown in FIG. 7, the contact point 707 is in quadrant Q1-Q2 ofthe resistive track 702, defined as the portion of the resistive trackbetween a first electrical sink 704 a and second electrical sink 704 b.The quadrant Q1-Q2 may be thought of as two separate resistors, namelyone resistor R1 extending from the first electrical sink 704 a to thecontact point 707, and a second resistor R2 extending from the secondelectrical sink 704 b to the contact point 707.

Likewise, the voltage at the second contact member's 708 contact point709 is a function of the position of the second contact member 708 alongthe second resistive track 703. The contact member's contact point 709is between two ground taps, unless it is at a ground tap. For exampleand as shown in FIG. 7, the contact point 709 is in quadrant Q2-Q3 ofthe resistive track 703, defined as the portion of the resistance memberbetween a third electrical sink 704 c and a fourth electrical sink 704d. The quadrant Q2-Q3 may be thought of as two separate resistors,namely a third resistor R3 extending from the third electrical sink 704c to the contact point 709, and a fourth resistor R4 extending from thefourth electrical sink 704 d to the wiper contact point 709.

Although four electrical sinks 704 are illustrated in FIG. 7, it shouldbe appreciated that more or fewer electrical sinks may be provided. Theresolution of the rotary encoder 300 may vary based on the number n ofelectrical sinks provided. As shown in FIG. 7, the first contact member706 and the second contact member 708 may be offset from one another byan angle α=π.

The embodiment of FIG. 7 may have substantially the same circuitry asdiscussed above with respect to FIG. 5. That is, a voltage dividercircuit is set up based on the contact position of the first contactmember 706 on the first resistive track 702 and a second voltage dividercircuit is formed based on the contact position of the second contactmember 708 on the second resistive track 703. As the first contactmember 706 is rotated around the shaft 710 axis, the first and secondresistances R1, R2 vary. An input of an m-bit Analog-to-DigitalConverter (ADC) may be electrically coupled to the contact point of thefirst contact member 706. The m-bit ADC may output a digitized signalWd1 that is the voltage measured at the contact point between the firstcontact member 706 and the first resistive track 702. The signal at thiscontact point 707 may be detected and monitored over time in order todetermine a rotational position of the first contact member 706 and thusan angular position of the shaft, as discussed below with reference toFIG. 8.

Similarly, as the second contact member 708 is rotated around the shaft710 axis, the third and fourth resistances R3, R4 vary. An input of anm-bit Analog-to-Digital Converter (ADC) may be electrically coupled tothe contact point of the second contact member 708. The m-bit ADC mayoutput a digitized signal Wd2 of the voltage measured at this contactpoint between the second contact member 708 and the second resistivetrack 703. The digital signal Wd2 may be detected and monitored overtime in order to determine a rotational position of the second contactmember 708 and thus an angular position of the shaft, as discussed belowwith reference to FIGS. 8A-8B.

Turning now to FIGS. 8A-8B, the outputs at the contact points 707 and709 are plotted as voltages cycling between zero and Vref as a functionof contact member position around the axis of the shaft (e.g., thecontact points and the angle Θ vary as the shaft revolves and a contactmember travels along its resistive track). Plot 802 is a plot of thevoltage of the first contact member 706 as measured at its contact point707, and plot 804 is a plot of the voltage of the second contact member708 as measured at its contact point 709.

With respect to FIG. 8A, rotating the shaft 710 (or other user-rotatableelement) causes rotation of the first and second contact members 706,708 and changes the shaft's angular position. As the contact membersrotate around the shaft (e.g., the angle Θ changes), their outputsignals vary between zero and Vref. The output of the first contactmember is shown as plot 802 and the output of the second contact memberis shown as plot 804.

Due to the layout of the resistive tracks 702, 703 around the shaft 710,plots 802 and 804 may peak at Vref at different angles of rotation Θ.This information may be used to determine the rotational direction ofthe contact members 706, 708 around the shaft 710. For example, FIG. 8Amay depict a rotation of the shaft 410 in a first direction (e.g.,clockwise in FIG. 7). Similarly, FIG. 8B may depict a rotation of theshaft 710 in a second direction (e.g., counter-clockwise in FIG. 7).

With reference now to FIGS. 9A-9B, a simplified electrical diagram 900of another embodiment of a rotary encoder is shown. As with the otherrotary encoders discussed herein, the embodiment shown in FIGS. 9A-9Bmay be used as, or in, a crown of an electronic device (such as anelectronic watch). FIG. 9A illustrates the electrical connectivity of arotary encoder similar to the rotary encoder in FIG. 7 but with aconductive output track 902 and a somewhat different arrangement ofresistive tracks 904, 906. The resistive tracks 904, 906 and conductiveoutput track 902 may be circular, concentric, and positioned coaxiallyaround a shaft 908. The resistive tracks 904, 906 and conductive outputtrack 902 may be supported by a contact surface of a base of the rotaryencoder.

The first resistive track 904 (e.g., a resistance member) may bepositioned coaxially around the shaft 908 (or other rotatable element).A first contact member 910 (e.g., a first wiper) may contact the firstresistive track 904 at a first contact point 912 and travel along thefirst resistive track 904 as the shaft 908 rotates with respect to anaxis of the rotary encoder. A first array of electrical sinks 914 a, 914b, 914 c, 914 d (which act as the ground taps previously described) maybe provided around the first resistive track 904. The total resistanceof the first resistive track 904 may be R1, and the first resistivetrack 904 may have uniform resistivity as discussed above (e.g., auniform resistance per unit volume of material forming the resistivetrack). A second resistive track 906 may be positioned radially inwardfrom the first resistive track 904 and disposed around the shaft 908.The total resistance of the second resistive track 906 may be R2, andthe second resistive track 906 may have uniform resistivity as discussedabove (e.g., a uniform resistance per unit volume of material formingthe resistive track). R1 and R2 may be equal or unequal. A secondcontact member 916 (a second wiper) may contact the second resistivetrack 906 at a second contact point 918 and travel along the secondresistive track 906 as the shaft 908 rotates with respect to the axis ofthe rotary encoder. The radius of the second resistive track 906 may beless than the radius of the first resistive track 904. A second array ofelectrical sinks 914 e, 914 f, 914 g, 914 h may be spaced around thesecond resistive track 906. In one embodiment, the electrical sinks 914a-h may be equally spaced about each of the first resistive track 904and the second resistive track 906. The electrical sinks 914 a-h areindicated by diamonds in FIG. 9A, while voltage inputs 920 a-h(discussed below) are indicated by triangles. The shape is arbitrary andintended only to provide visual differentiation between the two.

The electrical sinks 914 a-h may divide the first resistive track 904and the second resistive track 906 into multiple segments. An array ofvoltage inputs may include a first array of voltage inputs 920 a, 920 b,920 c, 920 d connected to the first resistive track 904 and a secondarray of voltage inputs 920 e, 920 f, 920 g, 920 h connected to thesecond resistive track 906. Each voltage input 920 a-h may be positionedbetween a set of adjacent electrical sinks (e.g., voltage input 920 amay be positioned between electrical sinks 914 a and 914 b, voltageinput 920 b may be positioned between electrical sinks 914 b and 914 c,etc.).

The conductive output track 902 may be positioned radially inward fromthe second resistive track 906 and disposed around the shaft 908. Theradius of the conductive output track 902 may be less than the radius ofthe second resistive track 906. The conductive output track 902 may beelectrically connected to a voltage output 922 via a conductor 924(e.g., a conductive trace, wire, etc.). In alternative embodiments, theconcentric relationships of the tracks may differ (e.g., the resistivetracks 904, 906 may be interior to the conductive output track 902).

The first and second contact members 910, 916 may be electricallyconnected and coupled (affixed) to the shaft 908. In some examples, thefirst and second contact members 910, 916 may be coupled to a single arm926 (e.g., a rotor) that is affixed to and rotates with the shaft 908.The entirety of the arm 926 may be conductive, or the arm 926 mayinclude conductive traces or wires that electrically connect the firstand second contact members 910, 916. The first contact member 910 may beoffset by an angle α (about the shaft 908) from the second contactmember 916. Here, α=π. A third contact member 928 (i.e., a third wiper)may be electrically connected to the first and second contact members910, 916 and coupled to an arm 928 (which arm 928 may be configuredsimilarly to the arm 926, replaced by a portion of the shaft 908 thatextends over the resistive tracks 904, 906, etc.). The third contactmember 928 may contact the conductive output track 902 at a thirdcontact point 930. The third contact member 928 may travel along,contact, or wipe the conductive output track 902 as the shaft 908rotates with respect to the conductive output track 902.

During rotation of the shaft 908 with respect to the axis of the rotaryencoder, the angles of rotation (Θ) associated with the first contactmember 910 and the second contact member 916 change with rotation of theshaft 908, and thus the angles of rotation (or locations) of the firstcontact point 912 and the second contact point 918 change with respectto an axis of the rotary encoder.

As shown in FIG. 9B, the rotary encoder may further include one or moreswitches 932 configured to electrically activate the first resistivetrack 904 while electrically floating the second resistive track 906,and to electrically activate the second resistive track 906 whileelectrically floating the first resistive track 904. For purposes ofthis description, a resistive track is electrically active when acurrent is intentionally induced to flow through the resistive track. Asshown, the one or more switches 932 may include a first multiplexer 934and a second multiplexer 936. The first multiplexer 934 may have aninput 938 configured to receive a voltage (e.g., Vdd), a first output940 to which the voltage may be applied (as Vdd_A) when the firstmultiplexer 934 is placed in a first state (e.g., a logic “0” state),and a second output 942 to which the voltage may be applied (as Vdd_B)when the first multiplexer 934 is placed in a second state (e.g., alogic “1” state). The first output 940 may be coupled to the first arrayof voltage inputs 920 a-d and the second output 942 may be coupled tothe second array of voltage inputs 920 e-h. The second multiplexer 936may have an input 944 configured to be coupled to ground, a first output946 to which the ground may be connected (as Gnd_A) when the secondmultiplexer 936 is placed in a first state (e.g., a logic “0” state),and a second output 948 to which the ground may be connected (as Gnd_B)when the second multiplexer 936 is placed in a second state (e.g., alogic “1” state). The first output 946 may be coupled to the first arrayof electrical sinks 914 a-d, and the second output 948 may be coupled tothe second array of electrical sinks 914-e-h. In some examples, thecontrol inputs of the first multiplexer 934 and the second multiplexer936 may be electrically connected at a node 950 to which a commoncontrol signal (e.g., a binary control signal, CTRL) may be applied. Thecommon control signal may alternately place each multiplexer 934, 936 inthe logic “0” state or the logic “1” state.

When the first resistive track 904 is electrically active, and asrotation of the shaft 908 with respect to the axis of the rotary encodercauses the location of the first contact point 912 to change withrespect to the first resistive track 904, the voltage at the firstcontact point 912 changes (i.e., the voltage is a variable voltage).Similarly, when the second resistive track 906 is electrically active,and as rotation of the shaft 908 with respect to the axis of the rotaryencoder causes the location of the second contact point 918 to changewith respect to the second resistive track 906, the voltage at thesecond contact point 918 changes (i.e., the voltage is a variablevoltage). Because just one of the resistive tracks 904, 906 iselectrically active at a time (while the other resistive track isfloating), the voltages at the first contact point 912 and the secondcontact point 918 may be alternately output on the conductive outputtrack 902. Despite the variance in the voltages at the first contactpoint 912 and the second contact point 918, the first resistive track904, second resistive track 904, and/or other components of the rotaryencoder may be configured to maintain a predetermined offset between thevoltages.

Based on the voltages outputted on the conductive output track 902 (orat output 922), and the predetermined offset between the voltages, aprocessor may determine an angle of rotation of the first contact member910, the second contact member 916, or the shaft 908. The processor mayalso or alternatively determine a direction of rotation or speed ofrotation of the shaft 908.

The circuit shown in FIG. 10 represents the first contact member 910contacting the first resistive track 904 and the second contact member916 contacting the second resistive track 906. Each of the first andsecond resistive tracks is modeled as a set of resistors separated bygrounds, in accordance with the diagram of FIG. 9A. As shown in FIG. 10,the first resistive track 904 may be electrically activated by couplingVdd_A to the first array of voltage inputs 920 a-d and coupling Gnd_A tothe first array of electrical sinks 914 a-d. Alternatively, the secondresistive track 906 may be electrically activated by coupling Vdd_B tothe second array of voltage inputs 920 e-h and coupling Gnd_B to thesecond array of electrical sinks 914 e-h. The voltages at the first andsecond contact points 912, 918 may be alternately output at the voltageoutput 922 (as Vout) via the first contact member 910, arm 926, andconductive output track 902 (see FIG. 9A), and via the second contactmember 916, arm 926, and conductive output track 902. Each of the firstcontact member 910, second contact member 916, arm 926, and conductiveoutput track 902 may be associated with an impedance and consequentvoltage drop that affects the voltage obtained from the first or secondcontact point 912, 918.

Turning now to FIG. 11, an example of the voltages at the first contactpoint 912 and second contact point 918 (as discussed above in FIGS. 9A,9B, and 10) are plotted as voltages cycling between zero and a maximumvoltage Vref (e.g., Vdd_A or Vdd_B). The figure illustrates the voltagesas a function of a rotation angle Θ, which is the angle between acontact point and a zero-angle point of the resistive tracks 904, 906(e.g., where Θ=0). Plot 1102 may be a plot of the voltage at the firstcontact point 912, and plot 1104 may be a plot of the voltage at thesecond contact point 918. As shown in FIG. 11, as the shaft 908 of therotary encoder shown in FIG. 9A is rotated (e.g., as its angle ofrotation or angular position changes), causing rotation of the first andsecond contact members 910, 916, the voltages vary between zero andVref. Plots 1102 and 1104 are out of phase by a constant, predeterminedoffset, and are thus considered to be in quadrature. The amount ofquadrature or predetermined offset may depend on the angle α between thefirst and second contact members 910, 916. By determining a phasedifference between plots 1102 and 1104, the direction of rotation of theshaft 908 can be determined, as can the shaft's angular position. Suchdeterminations may be made by any suitable processor 202.

FIG. 12 shows an example of a timing diagram for the rotary encodershown in FIGS. 9A and 9B. As shown, the first resistive track 904 may beelectrically activated during a first time period 1202 by connecting thefirst array of voltage inputs 920 a-d to Vdd_A and the first array ofelectrical sinks 914 a-d to Gnd_A. The second resistive track 906 may beelectrically isolated (held at a high impedance state, z) during thefirst time period 1202. Similarly, the second resistive track 906 may beelectrically activated during a second time period 1204 by connectingthe second array of voltage inputs 920 e-h to Vdd_A and the second arrayof electrical sinks 914 e-h to Gnd_A. The first resistive track 904 maybe electrically isolated (held at a high impedance state, z) during thesecond time period 1204. One or more switches, such as the firstmultiplexer 934 and the second multiplexer 936, may be operated toprovide alternating instances of the first time period 1202 and thesecond time period 1204. In some examples, electrical activation of thefirst resistive track 904 or the second resistive track 906 may requireassertion of an enable (EN) signal 1206. During each of the first timeperiod 1202 and the second time period 1204, an ADC may obtain one ormore samples 1208, 1210 of the voltage at the first contact point 912 orthe second contact point 918. Obtaining multiple samples during each ofthe first time period 1202 and the second time period 1204 may improvedirection of rotation or speed of rotation determinations.

With reference now to FIG. 13, a simplified electrical diagram 1300 ofanother embodiment of a rotary encoder is shown. FIG. 13 illustrates theelectrical connectivity of a rotary encoder similar to the rotaryencoder in FIGS. 9A-9B, but with a single resistive track 1302 andmultiple conductive output tracks 1304, 1306. The resistive track 1302and conductive output tracks 1304, 1306 may be circular, concentric, andpositioned coaxially around a shaft 1308. The resistive track 1302 andconductive output tracks 1304, 1306 may be supported by a contactsurface of a base of the rotary encoder.

The resistive track 1302 (i.e., a resistance member) may be positionedcoaxially around the shaft 1308 (or other rotatable element). A firstcontact member 1310 (i.e., a first wiper) may contact the resistivetrack 1302 at a first contact point 1312 and travel along the resistivetrack 1302 as the shaft 1308 rotates with respect to an axis of therotary encoder. A second contact member 1314 (i.e., a second wiper) maycontact the resistive track 1302 at a second contact point 1316 andtravel along (e.g., wipe) the resistive track 1302 as the shaft 1308rotates with respect to the axis of the rotary encoder. The firstcontact member 1310 may be electrically connected to a first arm 1318(e.g., a first rotor) that is affixed to and rotates with the shaft1308. The second contact member 1314 may be electrically connected to asecond arm 1320 (e.g., a second rotor) that is affixed to and rotateswith the shaft 1308. The first arm 1318 may be electrically isolatedfrom the second arm 1320. The entireties of the first and second arms1318, 1320 may be conductive, or the first and second arms 1318, 1320may include conductive traces or wires that electrically connect to thefirst or second contact member 1310, 1314. In other examples, the firstand second contact members 1310, 1314 may be affixed to the shaft 1308in other ways (e.g., the shaft 1308 may have a portion that extendsoutward from the axis of the rotary encoder and over the resistive track1302, and the first and second contact members 1310, 1314 may be formedon or attached to a surface of the shaft 1308 that faces the resistivetrack 1302). The first contact member 1310 may be offset by an angle α(about the shaft 1308) from the second contact member 1310.

An array of electrical sinks 1322 a, 1322 b, 1322 c, 1322 d (which actas the ground taps previously described) may be provided around theresistive track 1302. The total resistance of the resistive track 1302may be R, and the resistive track 1302 may have uniform resistivity asdiscussed above (e.g., a uniform resistance per unit volume of materialforming the resistive track). In one embodiment, the electrical sinks1322 a-d may be equally spaced about the resistive track 1302. Theelectrical sinks 1322 a-d may divide the resistive track 1302 intomultiple segments. An array of voltage inputs 1324 a, 1324 b, 1324 c,1324 d may also be connected to the resistive track 1302. Each voltageinput 1324 a-d may be positioned between a set of adjacent electricalsinks (e.g., voltage input 1324 a may be positioned between electricalsinks 1322 a and 1322 b, voltage input 1324 b may be positioned betweenelectrical sinks 1322 b and 1322 c, etc.).

A first conductive output track 1304 and a second conductive outputtrack 1306 may be positioned radially inward from the resistive track1302 and disposed around the shaft 1308. The radius of the firstconductive output track 1304 may be less than the radius of theresistive track 1302, and the radius of the second conductive outputtrack 1306 may be less than the radius of the first conductive outputtrack 1304. The first conductive output track 1304 may be electricallyconnected to a first voltage output 1326 via a first conductor 1328(e.g., a conductive trace, wire, etc.), and the second conductive outputtrack 1306 may be electrically connected to a second voltage output 1330via a second conductor 1332. In alternative embodiments, the concentricrelationships of the tracks may differ (e.g., the resistive track 1302may be interior to the conductive output tracks 1304, 1306).

A third contact member 1334 (e.g., a third wiper) may be electricallyconnected to the first contact member 1310 and coupled to the first arm1318 (or otherwise affixed to the shaft 1308). The third contact member1334 may contact the first conductive output track 1304 at a thirdcontact point 1336. The third contact member 1334 may contact, travelalong, or otherwise wipe the conductive output track 1304 as the shaft1308 rotates with respect to the axis of the rotary encoder. A fourthcontact member 1338 (e.g., a fourth wiper) may be electrically connectedto the second contact member 1314 and coupled to the second arm 1324 (orotherwise affixed to the shaft 1308). The fourth contact member 1338 maycontact the second conductive output track 1306 at a fourth contactpoint 1340. The fourth contact member 1338 may contact or wipe thesecond conductive output track 1306 as the shaft 1308 rotates withrespect to the axis of the rotary encoder.

During rotation of the shaft 1308 with respect to the axis of the rotaryencoder, the angles of rotation (Θ) associated with the first contactmember 1310 and the second contact member 1314 change with rotation ofthe shaft 1308, and thus the angles of rotation (or locations) of thefirst contact point 1312 and the second contact point 1316 change withrespect to the axis of the rotary encoder.

As rotation of the shaft 1308 with respect to the axis of the rotaryencoder causes the locations of the first and second contact points1312, 1316 to change with respect to the resistive track 1302, thevoltages at the first and second contact points 1312, 1316 change (e.g.,the voltages are variable voltages). The voltage at the first contactpoint 1312 may be output via the first conductive output track 1304, andthe voltage at the second contact point 1316 may be output via thesecond conductive output track 1306. Despite the variance in thevoltages at the first contact point 1312 and the second contact point1316, the resistive track 1302 and/or other components of the rotaryencoder may be configured to maintain a predetermined offset between thevoltages.

Based on the voltages (Vout0, Vout1) outputted on the first and secondconductive output tracks 1304, 1306 (or at outputs 1326 and 1330), andthe predetermined offset between the voltages, a processor may determinean angle of rotation of the first contact member 1310, the secondcontact member 1310, or the shaft 1308. The processor may also oralternatively determine a direction of rotation or speed of rotation ofthe shaft 1308.

The circuit shown in FIG. 14 represents the first and second contactmembers 1310, 1314 contacting the resistive track 1302. As shown in FIG.14, the resistive track 1302 may be electrically activated by couplingVdd to the array of voltage inputs 1324 a-d and coupling Gnd to thearray of electrical sinks 1322 a-d. The voltages at the first and secondcontact points 1312, 1316 may be simultaneously output at the first andsecond voltage outputs 1326, 1330, as Vout_0 and Vout_1, via the firstcontact member 1310, first arm 1318, and first conductive output track1304 (see FIG. 13), and via the second contact member 1314, second arm1320, and second conductive output track 1306. Each of the first contactmember 1310, second contact member 1314, first arm 1318, second arm1320, first conductive output track 1304, and second conductive outputtrack 1306 may be associated with an impedance and consequent voltagedrop that affects the voltage obtained from the first or second contactpoint 1312, 1316. The voltages at the first contact point 1312 andsecond contact point 1316 may be plotted as voltages cycling betweenzero and a maximum voltage Vref (e.g., Vdd), with Vout_0 being plottedas plot 1102 in FIG. 11 and Vout_1 being plotted as plot 1104 in FIG.11.

With reference now to FIG. 15, a simplified electrical diagram 1500 ofanother embodiment of a rotary encoder is shown. This rotary encoder maybe used as, or in, a crown of an electronic device, similar to otherrotary encoders discussed herein. FIG. 15 illustrates the electricalconnectivity of a rotary encoder with a single resistive track 1502 anda single conductive output track 1504. The resistive track 1502 andconductive output track 1504 may be circular, concentric, and/orpositioned coaxially around a shaft 1506. The resistive track 1502 andconductive output track 1504 may be supported by a contact surface of abase of the rotary encoder.

The resistive track 1502 (or any other resistance member) may bepositioned coaxially around the shaft 1506 (or other rotatable element),but may have a radial gap 1508 in its circumference. A first contactmember 1510 (i.e., a first wiper) may contact the resistive track 1502at a first contact point 1512 and wipe (e.g. travel along) the resistivetrack 1502 as the shaft 1506 rotates with respect to an axis of therotary encoder. A second contact member 1514 (a second wiper) maycontact the resistive track 1502 at a second contact point 1516 and wipethe resistive track 1502 as the shaft 1506 rotates with respect to theaxis of the rotary encoder. The total resistance of the resistive track1502 may be R, and the resistive track 1502 may have uniform resistivityas discussed above (e.g., a uniform resistance per unit volume ofmaterial forming the resistive track).

A first end 1518 of the resistive track 1502 may be electricallyconnected to a voltage input 1520, which voltage input 1520 may receivea voltage such as Vdd. In some examples, the voltage input 1520 may becoupled to the first end 1518 of the resistive track 1502 via a resistor1522 (e.g., a resistive trace, a wire, etc.). As shown in FIG. 15, aless resistive conductor 1524, or other more or less resistive elementsmay also be used to couple the voltage input 1520 to the first end 1518of the resistive track 1502. A reference voltage output 1526 may also becoupled to the first end 1518 of the resistive track 1502. A second end1528 of the resistive track 1502 may not be electrically connected toother elements.

The conductive output track 1504 may be positioned radially inward fromthe resistive track 1502 and disposed around the shaft 1506. The radiusof the conductive output track 1504 may be less than the radius of theresistive track 1502. The conductive output track 1504 may beelectrically connected to a constant current regulation circuit 1530. Inalternative embodiments, the concentric relationship of the tracks maydiffer (e.g., the resistive track 1502 may be interior to the conductiveoutput track 1504, the two may be positioned such that they are notseparated by an equal distance around their circumferences, and so on).The constant current regulation circuit 1530 supplies a constant currentto the conductive output track 1504, thereby enabling the voltage Voutto change as the contact member traverses the track, as described below.It should be appreciated that other embodiments described herein maylikewise include constant current sources, and that any constant currentsource may be the illustrated constant current regulation circuit 1530.

The first and second contact members 1510, 1514 may be electricallyconnected and coupled to a single arm 1532 (e.g., a rotor) that isaffixed to and rotates with the shaft 1506. The entirety of the arm 1532may be conductive, or the arm 1532 may include conductive traces orwires that electrically connect the first and second contact members1510, 1514. In other examples, the first and second contact members1510, 1514 may be affixed to the shaft 1506 in other ways (e.g., theshaft 1506 may have a portion that extends outward from the axis of therotary encoder and over the resistive track 1502, and the first andsecond contact members 1510, 1514 may be formed on or attached to asurface of the shaft 1506 that faces the resistive track 1502). Thefirst contact member 1510 may be offset by an angle α (about the shaft1506 from the second contact member 1514. Here, α=π. A third contactmember 1534 (i.e., a third wiper) may be electrically connected to thefirst and second contact members 1510, 1514 and coupled to the arm 1532(or otherwise affixed to the shaft 1506). The third contact member 1534may contact the conductive output track 1504 at a third contact point1536. The third contact member 1534 may contact or wipe the conductiveoutput track 1504 as the shaft 1506 rotates with respect to the axis ofthe rotary encoder.

During rotation of the shaft 1506 with respect to the axis of the rotaryencoder, the angles of rotation (Θ) associated with the first contactmember 1510, the second contact member 1514, and the third contactmember 1534 change with rotation of the shaft 1506, and thus the anglesof rotation (or locations) of the first contact point 1512, the secondcontact point 1516, and the third contact point 1536 change with respectto the axis of the rotary encoder.

As rotation of the shaft 1506 with respect to the axis of the rotaryencoder causes the locations of the first and second contact points1512, 1516 to change with respect to the resistive track 1502, thevoltage at the third contact point 1516 changes (thus, the voltage is avariable voltage). The voltage (Vout) at the third contact point 1516may be output via the conductive output track 1504.

Based on the voltage (Vout) outputted on the conductive output track1504, and a reference voltage (Vref) that is outputted at the referencevoltage output 1526, a processor may determine an angle of rotation ofthe first contact member 1510, the second contact member 1514, the thirdcontact member 1534, or the shaft 1506. The processor may also oralternatively determine a direction of rotation or speed of rotation ofthe shaft 1506.

The circuit 1600 shown in FIG. 16 represents the first and secondcontact members 1510, 1514 contacting the resistive track 1502. As shownin FIG. 16, the reference voltage output 1526 may be coupled to thevoltage input 1520 via the resistor 1522, and the resistive track 1502may be coupled between the reference voltage output 1526 and theconstant current regulation circuit 1530. The voltage (Vout) at thethird contact point 1516 may be based on the locations of the firstcontact point 1512 and the second contact point 1516 with respect to theresistive track 1502. The constant current regulation circuit 1530ensures that the current provided to the conductive output track 1504 isinvariant, and thus that the voltage changes in a known fashion as thecontact member traverses (wipes) the conductive output track 1504. Itshould be appreciated that the constant current regulation circuit isnot electrically connected to the resistive track 1502.

FIG. 17 illustrates an example plot 1702 of the difference between thevoltage (Vout) that is output via the conductive output track 1504 andthe reference voltage (Vref) that is output via the reference voltageoutput 1526 (as discussed above in FIG. 15). The voltage differencecycles between zero and a maximum voltage Vref. The figure illustratesthe voltages as a function of a rotation angle Θ, which is the anglebetween a contact point and a zero-angle point of the resistive track1502 (e.g., where Θ=0). As shown in FIG. 17, as the shaft 1506 isrotated (e.g., as its angle of rotation or angular position changes),causing rotation of the first, second, and third contact members 1510,1514, 1534, the voltage difference varies between zero and Vref in asawtooth pattern. The slope direction of the sawtooth pattern isindicative of the direction of rotation of the shaft 1506.

With reference now to FIG. 18, another embodiment of a compact rotaryencoder 1800 is illustrated for use as a crown in an electronic device,such as electronic device 100. In some embodiments the rotary encoder1800 may be coupled to the input device 106 of the electronic device 100such that a shaft 1806, or other rotatable element, of the rotaryencoder 1800 rotates when the input device 106 rotates. As discussedabove, in some embodiments the input device 106 may be the rotatingcrown of an electronic watch. The rotary encoder 1800 may include a base1802, cover 1804, and a contact surface 1803 of the base 1802. The cover1804 may include an aperture 1808 through which a rotating shaft 1806passes, such that the shaft is at least partially received within thehousing. In some embodiments, the cover 1804 may be a housing of anelectronic device in which the rotary encoder is at least partiallyenclosed. For example, a knob, portion of the shaft, or otheruser-manipulable element may protrude from an electronic device housing.A user may turn the user-manipulable element, thereby causing the shaft1806 to rotate about an axis extending along a length of the shaft. Auser may rotate a crown of an electronic watch in this fashion, as oneexample.

At least two capacitive members 1810 a, 1810 b may extend outwardly in aradial direction from the shaft 1806. The capacitive members 1810 a,1810 b may be coupled to the shaft 1806 and separated by an angle αaround the shaft 1806. It should be noted that although two capacitivemembers 1810 a, 1810 b are illustrated, more capacitive members 1810 maybe coupled to the shaft 1806 and separated by other angles α.

Each capacitive member 1810 a, 1810 b may have a known capacitance. Thecontact surface 1803 of the base 1802 may have a capacitance sensingregion 1814. The capacitance sensing region 1814 may include or definecapacitance sensors 1816. In some embodiments the capacitance sensingregion 1814 may be embedded or integral with the contact surface 1803.As shown in FIG. 18, the capacitance sensing region 1814 may be disposedcoaxially beneath the rotating shaft 1806 such that capacitive members1810 a, 1810 b rotate with respect to each other while maintaining apredetermined separation distance. That is, the capacitive members 1810a, 1810 b rotate angularly with the shaft 1806 and interact with thecapacitance sensors 1816 in the capacitance sensing region 1814 atdifferent points throughout a full rotation.

The rotary encoder 1800 may also include a group of electrical contacts1820 a-d. The group of electrical contacts 1820 a-d may be included inthe base 1802 and may be electrically coupled to the capacitive members1810 a, b and capacitance sensors 1816. Electrical contacts 1820 a-d mayprovide input and output control of elements of the rotary encoder 1800.

In a particular example, as shown in FIG. 19, a capacitive member 1810 aof the rotary encoder 1800 may substantially overlap a capacitancesensor 1816, at an example angle Θ of rotation. Accordingly, thecapacitance sensor 1816 which substantially aligns with capacitivemember 1810 a in FIG. 19 may detect a maximum capacitance of thecapacitive member 1810 a. Conversely, the capacitive member 1810 b inFIG. 19 overlaps only a portion of the capacitance sensor 1816.Therefore, the capacitance sensor corresponding to capacitive member1810 b may sense a capacitance between zero and the maximum capacitanceof the capacitive member 1810 b. As shown in FIG. 19, the capacitivemember 1810 a, 1810 b may be separated by an angle α. Analogous to theangle α described with respect to FIG. 4, the angle α may be chosen toensure that the first and second 1801 a, 1801 b output signals inquadrature, or output signals whose phases are offset by a preset amount(such as a predetermined offset).

FIG. 20 illustrates an exemplary plot of the digitized output of thecapacitance sensors 1816 as a function of rotation angle Θ of capacitivemembers 1810 a, b around the shaft 1806 (or other user-rotatableelement). Similar to the embodiment of FIG. 3 discussed above, the angleα between the first capacitive member 1810 a and the second capacitivemember 1810 b may be chosen to ensure that the capacitance signalsrecorded are in quadrature. The outputs of capacitance sensors 1816 maybe digitized by m-bit ADCs as discussed above with respect to FIGS. 5Aand 5B and 6A and 6B and plotted as voltages cycling between zero andVref as a function of wiper position Θ around the axis of the shaft1806. Plot 2002 is a plot of a digital voltage Wd1 of the firstcapacitive member 1810 a, and plot 2004 is a plot of a digital voltageWd2 of the second capacitive member 1810 b. As shown in FIG. 20A, as theshaft 1806 rotates, the signals Wd1 and Wd2 vary between zero and Vref.

The plots 2002 and 2004, corresponding to Wd1 and Wd2 respectively, areout of phase by a predetermined offset and thus considered to be inquadrature. The amount of quadrature (e.g., the predetermined offset)may result from the angle α between the first and second capacitivemembers 1810 a, b. By determining the phase difference between plots2002 and 2004, the rotational direction around the shaft 1806 can bedetermined.

FIG. 20A is a leading plot 2004 (e.g., the signals are positively out ofphase). Accordingly, FIG. 20A illustrates the capacitive members'outputs as the shaft 1806 rotates in a first direction (clockwise inFIG. 19). Similarly, FIG. 20B is a lagging plot 2004 (e.g., the signalsare negatively out of phase). Thus, FIG. 20B reflects rotation of theshaft 1806 in a second direction (counter-clockwise in FIG. 19).

FIG. 21 illustrates a method 2100 that may be performed to control afunction of an electronic device (e.g., the electronic device 100 ofFIG. 1) based on an angle of rotation of a first wiper of a rotaryencoder about an axis of a user-rotatable element (e.g., a shaft) of therotary encoder. The first wiper may be affixed to the user-rotatableelement and in contact a resistance member (e.g., a resistive track) ora conductive output track of the rotary encoder. The method 2100 may beperformed by a processor. In some examples, the rotary encoder may beany of the rotary encoders described in the present disclosure, or anyrotary encoder that incorporates aspects of the rotary encodersdescribed in the present disclosure.

At block 2102, the operation(s) may include receiving at least oneoutput signal from the rotary encoder. The output signal(s) may includeone or more voltages at one or more contact points between the firstwiper and the resistance member or conductive output track (e.g., thesignals or voltages output by any of the rotary encoders described withreference to FIGS. 1-20).

At block 2104, the operation(s) may include identifying, based on the atleast one output signal, the angle of rotation of the first wiper of therotary encoder about the axis of the rotatable element of the rotaryencoder.

At block 2106, the operation(s) may include controlling a function ofthe electronic device based on the angle of rotation.

In some examples of the method 2100, the at least one output signal mayinclude a first variable voltage associated with contact between thefirst wiper and the resistance member and a second variable voltageassociated with contact between a second wiper of the rotary encoder andanother resistance member (e.g., another resistive track) of the rotaryencoder (e.g., the voltages output by the rotary encoder described withreference to FIGS. 9-12). The second wiper may also be affixed to theuser-rotatable element, and the first variable voltage may be out ofphase with the second variable voltage by a predetermined offset. Inthese examples, identifying the angle of rotation may include comparingthe first variable voltage to the second variable voltage. In someexamples, the method 2100 may further include a direction of rotation orspeed of rotation of the user-rotatable element based on the firstvariable voltage, the second variable voltage, and the predeterminedoffset.

In some examples of the method 2100, the at least one output signal mayinclude a variable voltage and a reference voltage (e.g., the voltagesoutput by the rotary encoder described with reference to FIGS. 15-17).The variable voltage may be associated with contact between the firstwiper and the conductive output track, contact between a second wiper ofthe rotary encoder and the resistance member, and contact between athird wiper and the resistance member. The second wiper and the thirdwiper may be affixed to the user-rotatable element. The referencevoltage may be associated with a reference voltage output coupled to theresistance member. In these examples, identifying the angle of rotationmay include comparing the variable voltage to the reference voltage.

FIGS. 22A-24B generally depict examples of manipulating graphicsdisplayed on an electronic device through inputs provided by rotating acrown of the device. This manipulation (e.g., selection,acknowledgement, motion, dismissal, magnification, and so on) of agraphic may result in changes in operation of the electronic deviceand/or graphics displayed by the electronic device. Although specificexamples are provided and discussed, many operations may be performed byrotating and/or translating a crown incorporating a rotary encoder.Accordingly, the following discussion is by way of example and notlimitation.

FIG. 22A depicts a sample electronic device 2200 (shown here as anelectronic watch) having a rotatable crown 2210. The rotatable crown2210 may be, or incorporate, any rotary encoder described herein. Adisplay 2220 shows information and/or other graphics. In the currentexample, the display 2220 depicts a list of various items 2230, 2240,2250, all of which are example graphics.

FIG. 22B illustrates how the graphics shown on the display 2220 changeas the crown 2210 rotates (as indicated by the arrow 2270). Rotating thecrown 2210 causes the list to scroll or otherwise move on the screen,such that the first item 2230 is no longer displayed, the second andthird items 2240, 2250 each move upwards on the display, and a fourthitem 2260 is now shown at the bottom of the display. This is one exampleof a scrolling operation that can be executed by rotating the crown2210. Such scrolling operations may provide a simple and efficient wayto depict multiple items relatively quickly and in sequential order. Aspeed of the scrolling operation may be controlled by the speed at whichthe crown 2210 is rotated—faster rotation may yield faster scrolling,while slower rotation yields slower scrolling. The crown 2210 may betranslated (e.g., pushed inward toward the display 2220 or watch body)to select an item from the list, in certain embodiments.

FIGS. 23A-23B illustrate an example zoom operation. The display 2220depicts a picture 2300 at a first magnification, shown in FIG. 23A; thepicture 2300 is yet another example of a graphic. As the crown 2210 ofthe electronic watch 2200 rotates (again, illustrated by arrow 2270),the display may zoom into the picture, such that a portion 2310 of thepicture is shown at an increased magnification. This is shown in FIG.23B. The direction of zoom (in vs. out) and speed of zoom, or locationof zoom, may be controlled through rotation of the crown 2210, andparticularly through the direction of rotation and/or speed of rotation.Rotating the crown in a first direction may zoom in, while rotating thecrown in an opposite direction may zoom out. Alternately, rotating thecrown in a first direction may change the portion of the picture subjectto the zoom effect. In some embodiments, pressing the crown may togglebetween different zoom modes or inputs (e.g., direction of zoom vs.portion of picture subject to zoom). In yet other embodiments, pressingthe crown may return the picture 2300 to the default magnification shownin FIG. 23A.

FIGS. 24A-24B illustrate possible use of the crown 2210 to change anoperational state of the electronic watch 2200 or otherwise togglebetween inputs. Turning first to FIG. 24A, the display 2220 depicts aquestion 2400, namely, “Would you like directions?” As shown in FIG.24B, the crown 2210 may be rotated (again, illustrated by arrow 2270) toanswer the question. Rotating the crown provides an input interpreted bythe electronic watch 2200 as “yes,” and so “YES” is displayed as agraphic 2410 on the display 2220. Rotating the crown 2210 in an oppositedirection may provide a “no” input.

In the embodiment shown in FIGS. 24A-24B, the crown's rotation is usedto directly provide the input, rather than select from options in a list(as discussed above with respect to FIGS. 22A-22B).

As mentioned previously, rotational input from a crown of an electronicdevice may control many functions beyond those listed here. The crownmay rotate to adjust a volume of an electronic device, a brightness of adisplay, or other operational parameters of the device. The crown mayrotate to turn a display on or off, or turn the device on or off. Thecrown may rotate to launch or terminate an application on the electronicdevice. Further, translational input of the crown may likewise initiateor control any of the foregoing functions, as well.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. For example, certain embodiments may employ a resistivetrack, output track, and/or resistance member that is substantiallyflat. However, this need not be the case. Embodiments may employ tracksand/or members that vary in the Z dimension as well as within an X-Yplane. Some such tracks/members may have raised or lowered portions inorder to facilitate electrical routing, provide space for othercomponents of the embodiment or other components in an electronic devicehousing the embodiment, to ensure or enhance contact between a wiper andthe member or track in a specific region, and so on. Accordingly, itshould be understood that any and all of the embodiments describedherein may have non-planar tracks or other members.

Thus, the foregoing descriptions of the specific embodiments describedherein are presented for purposes of illustration and description. Theyare not targeted to be exhaustive or to limit the embodiments to theprecise forms disclosed. It will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

What is claimed is:
 1. An electronic watch, comprising: a housing; acrown at least partially positioned within the housing and configured toreceive rotational and translational input, and comprising: a shaft; aresistance member; and a set of wipers affixed to the shaft andoperative to travel along the resistance member during rotation of theshaft, the set of wipers providing an output based on multiple contactpoints between the set of wipers and the resistance member; a displaypositioned at least partially within the housing and configured todepict a graphic in response to at least one of the rotational input orthe translational input; an analog-to-digital converter electricallyconnected to the set of wipers, the analog-to-digital converterconfigured to provide a digital output corresponding to the output; anda processor configured to determine an angular position, a direction ofrotation, or a speed of rotation of the shaft using the digital output,and to manipulate the graphic in response to the determined angularposition, the direction of rotation, or the speed of rotation; whereineach wiper divides a resistance of the resistance member at each contactpoint, and a voltage at each contact point of the multiple contactpoints varies in response to rotation of the shaft.
 2. The electronicwatch of claim 1, wherein: the resistance member is circular; theresistance member has a constant resistance along its circumference; andthe set of wipers maintains constant contact with the resistance member.3. The electronic watch of claim 1, wherein: the resistance membercomprises a first segment and a second segment separated by a groundtap; the set of wipers comprises a first wiper and a second wiper; andduring rotation of the shaft, the first wiper divides the first segmentat a first contact point of the multiple contact points while the secondwiper divides the second segment at a second contact point.
 4. Theelectronic watch of claim 3, wherein a first resistance of the firstsegment is equal to a second resistance of the second segment.
 5. Theelectronic watch of claim 3, wherein: the first segment has a constantresistance; and the first contact point defines, in the first segment,two portions having a cumulative resistance equal to the constantresistance of the first segment.
 6. The electronic watch of claim 5,wherein a resistance of each of the two portions varies in response torotation of the shaft while maintaining the cumulative resistance equalto the constant resistance of the first segment.
 7. The electronic watchof claim 5, wherein the first wiper and the second wiper maintainelectrical contact with the resistance member during rotation of theshaft.
 8. The electronic watch of claim 1, wherein: the resistancemember comprises a first resistive track and a second resistive track;the electronic watch further comprises a switch configured toelectrically activate the first resistive track while electricallyfloating the second resistive track, and to electrically activate thesecond resistive track while electrically floating the first resistivetrack; the set of wipers comprises a first wiper that travels along thefirst resistive track and a second wiper that travels along the secondresistive track; the first wiper is electrically connected to the secondwiper; and the output comprises a first output associated with the firstwiper and a second output associated with the second wiper.
 9. Theelectronic watch of claim 1, wherein: the resistance member comprises aresistive track; the set of wipers comprises a first wiper that travelsalong the resistive track and a second wiper that travels along theresistive track; the first wiper is electrically isolated from thesecond wiper; and the output comprises a first output associated withthe first wiper and a second output associated with the second wiper.10. The electronic watch of claim 9, further comprising: a firstconductive output track; a second conductive output track; a third wiperaffixed to the shaft and electrically connected to the first wiper, andoperative to travel along the first conductive output track duringrotation of the shaft; and a fourth wiper affixed to the shaft andelectrically connected to the second wiper, and operative to travelalong the second conductive output track during rotation of the shaft.11. The electronic watch of claim 1, wherein: the resistance membercomprises a resistive track; the set of wipers comprises a first wiperthat travels along the resistive track and a second wiper that travelsalong the resistive track; the first wiper is electrically connected tothe second wiper; and the output comprises an output associated withboth the first wiper and the second wiper.
 12. The electronic watch ofclaim 11, further comprising: a voltage input; a resistor; a constantcurrent regulation circuit; and a reference voltage output, wherein theresistive track is coupled between the reference voltage output and theconstant current regulation circuit; and the voltage input is coupled tothe reference voltage output via the resistor.
 13. A crown for anelectronic watch, comprising: a resistance member on a contact surface;a rotatable shaft; an array of ground taps separating the resistancemember into segments of uniform resistivity; a first wiper and a secondwiper affixed to the rotatable shaft, the first wiper configured togenerate a first output based on a relative position of the first wiperwith respect to the resistance member and the second wiper configured togenerate a second output based on a relative position of the secondwiper with respect to the resistance member; and a processor configuredto determine at least one of an angular position, a direction ofrotation, or a speed of rotation of the rotatable shaft based on thefirst output and the second output, wherein: the crown is configured toreceive a rotational input and a translational input; and the firstwiper and the second wiper are affixed to the rotatable shaft such thatthe first wiper contacts the resistance member at a first segment thatis distinct from a second segment contacted by the second wiper.
 14. Thecrown of claim 13, wherein: a display is configured to depict a graphicin response to at least one of the rotational or translational input;and the processor is configured to manipulate the graphic in response tothe determined angular position, direction of rotation, or speed ofrotation.
 15. The crown of claim 13, wherein the array of ground taps ispositioned on the resistance member such that the segments have asubstantially similar size.
 16. The crown of claim 13, wherein theresistance member comprises a first resistive track and a secondresistive track, the crown further comprising: an array of voltageinputs connected to the resistance member, the array of voltage inputsincluding a voltage input positioned between each set of adjacent groundtaps along the resistance member; and a switch connected to at least thearray of voltage inputs and configured to electrically activate thefirst resistive track while electrically floating the second resistivetrack, and to electrically activate the second resistive track whileelectrically floating the first resistive track, wherein the first wiperis electrically connected to the second wiper.
 17. The crown of claim13, further comprising: a dome switch, wherein the rotatable shaft istranslatable and has a first end configured to depress and activate thedome switch in response to translation of the rotatable shaft.